In the Third Generation Partnership Project (3GPP), related to standardization of mobile communication systems, a relay station (relay node, RN) for relaying radio communication between a base station (evolved node B, ENodeB) and user equipment (UE) has been stipulated (Non-Patent Document 1). In Non-Patent Document 1, however, the movement of a relay station is not described, and, for example, inter-cell handover at a relay station is not supported.
A mobile relay system has been proposed in which a relay station is installed in a vehicle capable of moving while accommodating a large number of user equipments (for example, a railroad car), and the relay station relays radio communication between the accommodated user equipments and a base station (for example, Patent Document 1). In the mobile relay system, when the relay station moves, a base station (cell) to which the relay station belongs changes. Therefore, handover at the relay station needs to be supported.